1NM(1P) POSIX Programmer's Manual NM(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 nm — write the name list of an object file (DEVELOPMENT)
13
15 nm [-APv] [-g|-u] [-t format] file...
16 nm [-APv] [-efox] [-g|-u] [-t format] file...
17
19 The nm utility shall display symbolic information appearing in the
20 object file, executable file, or object-file library named by file. If
21 no symbolic information is available for a valid input file, the nm
22 utility shall report that fact, but not consider it an error condition.
23 The default base used when numeric values are written is unspecified.
25 On XSI-conformant systems, it shall be decimal if the -P option is not
26 specified.
27
29 The nm utility shall conform to the Base Definitions volume of
30 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
31 The following options shall be supported:
33 -A Write the full pathname or library name of an object on each
35 line.
36 -e Write only external (global) and static symbol information.
38 -f Produce full output. Write redundant symbols (.text, .data,
40 and .bss), normally suppressed.
41 -g Write only external (global) symbol information.
43 -o Write numeric values in octal (equivalent to -t o).
45 -P Write information in a portable output format, as specified
47 in the STDOUT section.
48 -t format Write each numeric value in the specified format. The format
50 shall be dependent on the single character used as the format
51 option-argument:
52 d decimal (default if -P is not specified).
54 o octal.
56 x hexadecimal (default if -P is specified).
58 -u Write only undefined symbols.
60 -v Sort output by value instead of by symbol name.
62 -x Write numeric values in hexadecimal (equivalent to -t x).
64
66 The following operand shall be supported:
67 file A pathname of an object file, executable file, or object-file
69 library.
70
72 See the INPUT FILES section.
73
75 The input file shall be an object file, an object-file library whose
76 format is the same as those produced by the ar utility for link edit‐
77 ing, or an executable file. The nm utility may accept additional imple‐
78 mentation-defined object library formats for the input file.
79
81 The following environment variables shall affect the execution of nm:
82 LANG Provide a default value for the internationalization vari‐
84 ables that are unset or null. (See the Base Definitions vol‐
85 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
86 ables for the precedence of internationalization variables
87 used to determine the values of locale categories.)
88 LC_ALL If set to a non-empty string value, override the values of
90 all the other internationalization variables.
91 LC_COLLATE
93 Determine the locale for character collation information for
94 the symbol-name and symbol-value collation sequences.
95 LC_CTYPE Determine the locale for the interpretation of sequences of
97 bytes of text data as characters (for example, single-byte as
98 opposed to multi-byte characters in arguments).
99 LC_MESSAGES
101 Determine the locale that should be used to affect the format
102 and contents of diagnostic messages written to standard
103 error.
104 NLSPATH Determine the location of message catalogs for the processing
106 of LC_MESSAGES.
107
109 Default.
110
112 If symbolic information is present in the input files, then for each
113 file or for each member of an archive, the nm utility shall write the
114 following information to standard output. By default, the format is
115 unspecified, but the output shall be sorted by symbol name according to
116 the collation sequence in the current locale.
117 * Library or object name, if -A is specified
119 * Symbol name
121 * Symbol type, which shall either be one of the following single
123 characters or an implementation-defined type represented by a sin‐
124 gle character:
125 A Global absolute symbol.
127 a Local absolute symbol.
129 B Global ``bss'' (that is, uninitialized data space) symbol.
131 b Local bss symbol.
133 D Global data symbol.
135 d Local data symbol.
137 T Global text symbol.
139 t Local text symbol.
141 U Undefined symbol.
143 * Value of the symbol
145 * The size associated with the symbol, if applicable
147 This information may be supplemented by additional information specific
149 to the implementation.
150 If the -P option is specified, the previous information shall be dis‐
152 played using the following portable format. The three versions differ
153 depending on whether -t d, -t o, or -t x was specified, respectively:
154 "%s%s %s %d %d\n", <library/object name>, <name>, <type>,
157 <value>, <size>
158 "%s%s %s %o %o\n", <library/object name>, <name>, <type>,
160 <value>, <size>
161 "%s%s %s %x %x\n", <library/object name>, <name>, <type>,
163 <value>, <size>
164 where <library/object name> shall be formatted as follows:
166 * If -A is not specified, <library/object name> shall be an empty
168 string.
169 * If -A is specified and the corresponding file operand does not name
171 a library:
172 "%s: ", <file>
175 * If -A is specified and the corresponding file operand names a
177 library. In this case, <object file> shall name the object file in
178 the library containing the symbol being described:
179 "%s[%s]: ", <file>, <object file>
182 If -A is not specified, then if more than one file operand is specified
184 or if only one file operand is specified and it names a library, nm
185 shall write a line identifying the object containing the following sym‐
186 bols before the lines containing those symbols, in the form:
187 * If the corresponding file operand does not name a library:
189 "%s:\n", <file>
192 * If the corresponding file operand names a library; in this case,
194 <object file> shall be the name of the file in the library contain‐
195 ing the following symbols:
196 "%s[%s]:\n", <file>, <object file>
199 If -P is specified, but -t is not, the format shall be as if -t x had
201 been specified.
202
204 The standard error shall be used only for diagnostic messages.
205
207 None.
208
210 None.
211
213 The following exit values shall be returned:
214 0 Successful completion.
216 >0 An error occurred.
218
220 Default.
221 The following sections are informative.
223
225 Mechanisms for dynamic linking make this utility less meaningful when
226 applied to an executable file because a dynamically linked executable
227 may omit numerous library routines that would be found in a statically
228 linked executable.
229
231 None.
232
234 Historical implementations of nm have used different bases for numeric
235 output and supplied different default types of symbols that were
236 reported. The -t format option, similar to that used in od and strings,
237 can be used to specify the numeric base; -g and -u can be used to
238 restrict the amount of output or the types of symbols included in the
239 output.
240 The compromise of using -t format versus using -d, -o, and other simi‐
242 lar options was necessary because of differences in the meaning of -o
243 between implementations. The -o option from BSD has been provided here
244 as -A to avoid confusion with the -o from System V (which has been pro‐
245 vided here as -t and as -o on XSI-conformant systems).
246 The option list was significantly reduced from that provided by histor‐
248 ical implementations.
249 The nm description is a subset of both the System V and BSD nm utili‐
251 ties with no specified default output.
252 It was recognized that mechanisms for dynamic linking make this utility
254 less meaningful when applied to an executable file (because a dynami‐
255 cally linked executable file may omit numerous library routines that
256 would be found in a statically linked executable file), but the value
257 of nm during software development was judged to outweigh other limita‐
258 tions.
259 The default output format of nm is not specified because of differences
261 in historical implementations. The -P option was added to allow some
262 type of portable output format. After a comparison of the different
263 formats used in SunOS, BSD, SVR3, and SVR4, it was decided to create
264 one that did not match the current format of any of these four systems.
265 The format devised is easy to parse by humans, easy to parse in shell
266 scripts, and does not need to vary depending on locale (because no Eng‐
267 lish descriptions are included). All of the systems currently have the
268 information available to use this format.
269 The format given in nm STDOUT uses <space> characters between the
271 fields, which may be any number of <blank> characters required to align
272 the columns. The single-character types were selected to match histori‐
273 cal practice, and the requirement that implementation additions also be
274 single characters made parsing the information easier for shell
275 scripts.
276
278 None.
279
281 ar, c99
282 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
284 Variables, Section 12.2, Utility Syntax Guidelines
285
287 Portions of this text are reprinted and reproduced in electronic form
288 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
289 table Operating System Interface (POSIX), The Open Group Base Specifi‐
290 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
291 Electrical and Electronics Engineers, Inc and The Open Group. In the
292 event of any discrepancy between this version and the original IEEE and
293 The Open Group Standard, the original IEEE and The Open Group Standard
294 is the referee document. The original Standard can be obtained online
295 at http://www.opengroup.org/unix/online.html .
296 Any typographical or formatting errors that appear in this page are
298 most likely to have been introduced during the conversion of the source
299 files to man page format. To report such errors, see https://www.ker‐
300 nel.org/doc/man-pages/reporting_bugs.html .
301IEEE/The Open Group 2017 NM(1P)